Mercury switch in which time delay is obtained by adjustable metering of a non-conductive liquid



June 13, 1967 c. L. CUE ETAL 3,325,608

MERCURY SWITCH IN WHICH TIM ELAY IS OBTAINED BY USTABLE METERING OF A N -CONDUGTIVE LIQUID v Filed Aug. 9, l 2 Sheets-Sheet 1 pg .4 6F INVENTORS CLARA LEONA BY KENNETH r KEFr ATTORNEYS June 13, 1967 c. L. CUE Em. 3,325,608

MERCURY SWITCH IN WHICH TIME DELAY IS OBTAINED BY ADJUSTABLE METERING OF A NON-CONDUCTIVE LIQUID Filed Aug. 9, 1965 2 Sheets-Sheet 2 I02 INVENTORS CLARA LEONA CUE BY KENNETH T. WALKER ATTORNEYS United States Patent 3,325,608 MERCURY SWITCH IN WHICH TIME DELAY IS OBTAINED BY ADJUSTABLE METERING OF A NON-CONDUCTIVE LIQUID Clara Leona Cue, 1451 S. Frisco, Apt. 34 74120, and Kenneth T. Walker, 2245 S. Troost 74114, both of Tulsa, Okla.

Filed Aug. 9, 1965, er. No. 478,083 10 Claims. (Cl. 200-33) This invention relates to mercury switches, and more piafrticularly to mercury switches having a time-delay e ect.

Mercury switches for household and industrial use have become widely known and a large variety of structures have been described. Some of these structures describe switches which form a conductive circuit by rotating or tilting a housing containing the mercury and the spaced contacts, and permit the mercury to flow freely to make or break the circuit. Other switches provide a time-delay effect by permitting the mercury t0 flow through an orifice between two compartments. However, when the mercury flows through a small orifice, certain difficulties are encountered. -The cohesiveness of the mercury, the inability of the mercury to wet another surface, and the small amount of mercury generally employed in these switches sometime lead to unpredictible flow of the mercury through the orifice. Under the minute head provided by the small amount of mercury generally present, the mercury has a tendency to pass through the orifice as small globules and consequently the planned time-delay may vary considerably.

The time-delay mercury switch of this invention is designed to overcome the ditficulties described above by providing that the mercury which provides the conductive circuit is not directly involved in metering the time-delay, but rather the time-delay effect is brought about by the adjustable metering of a non-conductive liquid through an orifice. The non-conductive liquid is present in the switch with the mercury and is better suited for metering purposes than mercury because of its better flow characteristics which permit more accurate timing of the delay sequence.

The primary object of this invention is to provide an improved timedelay mercury switch.

Another object of this invention is to provide a timedelay mercury switch having an adjustable time-delay.

Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings wherein:

FIGURE 1 is a perspective and partial sectional view of the basic invention mounted in a standard electrical enclosure.

FIGURE 2 is a cross-sectional view of a modification of the invention in the off position.

FIGURE 3 is a cross-sectional view of the invention of FIGURE 2 in an initial on position.

FIGURE 4 is a cross-sectional View of the invention of FIGURE 2. in a final on position.

FIGURE 5 is a cross-sectional view of another modified form of the invention in an oif position.

FIGURE 6' is a cross-sectional view of a modified form of the invention in an on position.

FIGURE 7 is a cross-sectional view of another modified form of the invention in an off position.

FIGURE 8 is a cross-sectional view of the modified form of the invention of FIGURE 7 in an on position.

FIGURE 9 is a view along the line 9 -9 of FIGURE 2.

FIGURE 10 is a view along the line 1010 of FIG- URE 5.

FIGURE 11 is a view along the line 11-11 of FIG- URE 7.

Referring now to the drawings in detail, FIGURE 1 shows a conventional electrical enclosure 10 containing therein the rotatable time-delay mercury switch of the invention generally designated by the numeral 12 as it normally would be in the off position. The mercury switch 12 includes the cylindrical housing 14 which is made of any non-conductive material, for example, synthetic resins or other plastics. Molded integrally with the housing 14 is a toggle 16. The cylindrical switches 12 of FIGURES l, 2 and 4 have a Wall which is relatively thin in relation to the diameter of the cylindrical switch and is of substantially uniform thickness.

The mercury switch 12 shown in FIGURE 1 has a single pair of electrical contacts 18 and 20 penetrating opposite sides of the housing 14 and longitudinally opposite each other with each contact entering the interior of the housing for a short distance. The electrical contacts 18 and 20 are each connected to the electrical circuit to be controlled and when the contacts 18 and 20 are properly brought into conductive arrangement as hereinafter described the electrical circuit is closed.

Interior of the housing 14 is the bafiie 22, a wall portion extending integrally from the housing diametrically across the interior of the housing substantially to the opposite interior wall. The bafiie 22 is integral with the sides of the housing 14 and effectively divides the housing into two compartments, while at the same time forming a passage 24, more clearly shown in FIGURES 2, 3 and 4, between the end of the baffle 22 and the interior wall of the housing 14. The passage 24 is sufiicien-t to permit unobstructed flow of mercury from one side to the other. Adjacent that end of the baffle 22 where the bafiie 22 joins the interior wall of the housing 14 is a transverse passage 26 through the bafiie to permit communication between the two compartments on either side of bafile 22. A threaded opening 28 extends radially inwardly from the outer surface of housing 14 where the bafiie 22 joins the housing 14. Opening 28 communicates with smaller opening 30 which is a radial extension of the opening 28 and intersects passage 26. Needle valve 32 fits within the openings 28 and 30 and includes means such as slot 34 accessible from outside the housing 14 to various positions of the needle valve 32 so that the eliective opening of the passage 26 can be varied accordingly.

The interior of the housing is substantially filled with a layer of mercury 36 and a layer of non-conductive oil 38 immiscible with and of lower density than the mercury. Typically, the mercury and the oil each occupy approximately one half the volume of the interior of the housing 14.

FIGURES 2, 3 and 4 describe a modification of the invention shown in FIGURE 1 in that this modification includes a second pair of electrical contacts indicated by the numerals 40 and 42.

In operation, the mercury switch of FIGURE 1 provides for essentially instant on contact and for a timedelay when the switch is moved from the on position to the oil position. In the 01f position which is shown in FIG- URE 1 the electrical contacts 18 and 20 are slightly above the mercury level and within the non-conductive oil layer. The baflle 22 is positioned so that in the off position a lesser amount of the mercury is in the compartment containing the contacts 18 and 20 as is present in the second compartment. Also, the opening 24 is sufiiciently large so as not to hinder the flow of the mercury around the baflie. Thus, when the switch is rotated to the on position, the mercury already on that side of the baflie as the elec trical contacts merely moves slightly to bring the electrical contacts 18 and 20 into a conductive relationship. This initial seeking of the mercury for a new level is best shown in FIGURE 3 where the electrical contacts are almost immediately immersed in the mercury layer. Then, as also indicated by the modified version of FIGURES 2, 3 and 4, which include a second pair of electrical contacts 40- and 42, the mercury is seen to reach a final level as shown in FIGURE 4. The flow of the mercury around the baffle 22 from an initial level as shown in FIGURE 3 to a final level as shown in FIGURE 4 is controlled by the flow of the oil 38 through the passage 26. The timing of the flow of this oil through the passage 26 can be very accurately adjusted by the adjustment of the needle valve 32. The preferred oil to be used in the switch of this invention is a transformer oil of 28 A.P.I. gravity such as that which meets Federal specifications VV--401. Then, when the switch is in the final on position, the electrical contacts are immersed as shown in the mercury by the contact 18 in FIGURE 4. In this position the larger portion of the mercury is on the same side of the bafiie as the primary electrical contacts 18 and 20. Upon being rotated to the off position, the flow of the mercury around the baffle 22 will again be controlled by the passage of the oil through the passage 26, thus giving the switch its delay effect. By the proper positioning of the slide valve 32, and the contacts 18 and 20, and the proper choice of oil as to viscosity and density, the time-delay eifect may be varied from a few seconds to several minutes. The maintaining of the switch in a conductive relationship is beneficial where it is desired to keep the circuit closed for a short period after the switch is turned off, as for example to permit a person to turn the switch off when leaving a room and still have the light on for a few seconds.

FIGURE 9 describes the placement of the two pairs of electrical contacts employed in the embodiments of FIG- URES 2, 3 and 4. The first pair of electrical contacts is shown to be made up of the elements indicated by the numerals 18 and 20 and the second pair to be made up of elements and 42. The cross-sectional views of FIG- URES 2, 3 and 4 show only one contact of each pair, contacts 18 and 40 respectively, it being understood that contacts 20 and 42 enter the housing from the far sides and are not shown in the figures. FIGURE 2 shows this embodiment of the invention in the off position. FIGURE 3 shows this embodiment in the initial on position. FIG- URE 4 shows this embodiment in the final on position. The passage 24 between the end of baffle 22 and interior wall of the housing is of suflicient opening to permit the mercury to pass freely therethrough without encountering any time delay effect by restriction of the passage itself. As in the embodiment of FIGURE 1, the time-delay effect is brought about by the viscous flow of the oil 38 through passage 26, which passage has a variable opening provided by the operation of the needle valve 32. In the off position as shown in FIGURE 2 both pairs of electrical contacts represented in this figure by a single contact of each pair, that is, contacts 18 and 40, are slightly above the level of the mercury. In the initial on position shown in FIGURE 3 the rotation of the housing 14 causes mercury 36 to seek a new level such that both pairs of electrical contacts are immersed almost instantly in the mercury and the electrical circuits represented by each pair of contacts is brought into a conductive relationship. In the final on position described in FIGURE 4 the mercury 36 has achieved a stable condition for that position of the housing 14. The mercury 36 has flown freely around the end of bafile 22 but the flow of the mercury around this bafile 22 is slowed down and controlled by the flow of the immiscible liquid through the passage 26. the effective opening of passage 26 is determined by the adjustment of needle valve 32. In this modification of the invention the electrical contacts 40 and 42 are in a conductive relationship in the initial on position for only a short period of time until mercury 36 reaches the stable level for the on position. Thus, while there are two pairs of electrical contacts present, one pair is subject to a time delay on effect. The delay on is useful for controlling two electrical circuits with one circuit being on for only a brief period when the switch is turned on and the second circuit remaining on for a brief period after the switch is turned off. A particular use of this modification is in the circuit controlling fluorescent lights, where the first circuit which is on only briefly will replace the troublesome starters which are commonly employed in fluorescent lights. Of course, other circuit uses of this modification can be found.

FIGURES 5 and 6 describe a second modification of this invention. The cylindrical housing 14 includes a thickened portion 44 serving to reduce the volume of the housing and also to cooperate with the additional baffles in providing proper flow of mercury. The bafile 46 in the modification extends only partly across the interior diameter of the housing and is substantially thicker than baflle 22 of FIGURE 1. Extending longitudinal-1y through baffle 46 is bore 48 into which is fitted atn adjustable needle valve 50. Needle valve 50 is adjustable from the exterior of housing 14. Positioned so as to provide a relatively narrow passageway between thickened portion of the housing 14 and the larger portion of the interior of the housing is the second wall baflie 52. One section of the baffle 52 is a substantially straight wall member providing a narrow passage between that straight section of baflle 52 and the thickened wall portion 44. The other part of the baffle 52 is an arcuate member providing a narrow passage 54 between that arcuate member and the relatively thin wall of housing 14. Positioned between the second wall baflle 52 and the straight wall baffle 46 is the third wall baffie 56. Baffle 56 is integrally adjacent both straight wall baffle 46 and baffle 52 by means of joinder of the end portion of baflle 46 to the central part of baffle 52 and by the joinder of the end portion of 'baflle 56 to the arcuate portion of battle 52. The straight side of bafile 56, nearest straight wall member of baflle 52, provides the passage 58 between the two baffles 52 and 56 for the passage of fluid therethrough. At the end of baflle 56 adjacent the arcuate portion of baflle 52 is bore 60. Bore 60 provides communication between passage 58 and the larger compartment of housing 14. Adjacent the end of baffle 46 nearest baffle 56 is bore 62 which is adjustably closed by needle valve 50. Bore 52 provides communication between the compartments on either side of the straight wall bafile 46. As in the modifications shown in FIGURES 1 through 4, the modification shown in FIGURES 5 and 6 contain mercury 36, oil 38 and also contain an inert gas such as neon or argon instead of being filed completely with only mercury and oil. The pair of electrical contacts 66 and 68 enter the sides of the housing 14 as shown in FIGURE 10 and are positioned intermediate between bafifle 52 and the thickened wall portion 44 as described in FIGURES 5 and 6 in which only contact 68 is shown in these cross-sectional views.

In operation, the modification described in FIGURES 5 and 6 is designed :so that the electrical contacts 66 and 68 are exposed to either the mercury in the conductive position or the inert gas in the non-conductive position, and so that the time-delay effect which maintains the electrical contacts in a conductive position after the switch is turned off is provided by the flow of the oil 38 through the bore 62. In the off position shown in FIGURE 5 the mercury 36 occupies the lower portion of housing 14 and the electrical contacts 66 and 68 are exposed to the inert gas. When the mercury switch is rotated to the on position as shown in FIGURE 6, the positioning of the electrical contacts 66 and 68 close to the thickened portion of the wall 44 permits the circuit to be placed in conductive relationship almost immediately. The mercury drives the inert gas from between baflle 52 and thickened wall portion 44 into passage 54 and to the top of the housing. Also, in the on position shown in FIGURE 6 the oil 38 is seen to occupy the upper portion of a housing between baflie 46 and the'arcuate extremity of baflle 56. When the housing 14 is rotated to the off position,

the flow of mercury in the lower portion of the housing will be regulated by the flow of oil through the passage 62 controlled by the positioning of the needle valve 50. Thus, a time-delay effect will be established. When mercury 36 has finally settled to the lower portion of housing 14, the electrical contacts 66 and 68 will be surrounded by the inert gas 64 and not by the oil 38. It is considered that in some uses the immersion of the electrical contacts in oil and the removal therefrom will produce a sparking or arcing effect with the ultimate carbonization of the oil around the contacts. The use of the inert gas to enclose the contacts in the off position will prevent this effect. Although three immiscible fluids are present and a complicated arrangement of 'baflles and bores are provided, the tumbling of the mercury switch of this invention during shipment or before installation with the resultant movement of the fluids into cavities where they are not supposed to be will present no problem since the rotatiion of the mercury switch in its normal vertical position a few times will easily separate the fluids.

The further modification of the invention shown in FIGURES 7 and 8 is designed to provide for the employment of a plurality of electrical contacts wherein none of the contacts is exposed to the oil contained in the housing. In this modification the baflle 46 extends approximately to the center of the housing and adjacent its inner end and joins the three pronged wall portion 70 which has three straight walled radially extending members. Adjacent the point of joinder of battle 46 and three-pronged wall portion 70 is the bore 62 providing communication between the compartments on either side of wall 46. The bore 62 is adjustably varied by the needle valve 50 extending down the bore 48 of baflle 46. The housing 14 has thickened portions 72 which are constructed to include a circular depression 74 which acts as a passage around one arm of the three-pronged balfle 70. Positioned in the housing on one seide of the baflle 46 and bafile 70 is a thin wall portion having an arcuate member 76 and a straight wall member 78. The arcuate member 76 is essentially concentric with the interior wall of the housing 14 and together with the interior wall of the housing forms passage 80 therewith. The straight wall member 78 provides a large passage or compartment 82 between the walls 78 and the thickened portion 72. The straight wall member 78 together with the parallel arm of the three arm prong wall portion 70 provides the passage 84 between the two. The passage 84 communicates with the passage 86 formed by the end of the extending member of portion 70 and the arcuate member 76. In the diametrically opposite portion of the housing 14 is a similar arcuate member 88 adjoining the straight wall member 90. Similarly, a large passage 92 is provided between straight member 90 and the thickened portion 72. A passage 94 is provided between the interior walls of the housing 14 and the concentric arcuate member 88; between the straight wall member 90 and the substantially parallel member of wall portion 70 is passage 96. Also a passage 98 is provided around that member of the three-pronged member 70 extending closest to arcuate member 88 and the interior wall of arcuate member 88. This modificationof the invention provides for a plurality of electrical contacts, indicated by the numerals 100, 102 and 104 in FIGURE 11, of which the cross-sectional views of FIGURES 7 and 8 show the positions of contacts 100 and 104. The mercury 36, oil 38 and inert gas 65 occupy the portions of the housing 14 shown in FIGURES 7 and 8.

This embodiment contains the three electrical contacts 100, 102 and 104, positioned as shown in FIGURES 7,

8, and 11, and positioned so that in the initial on position all three electrical contacts are in a conductive relationship in the mercury layer and after the time-delay of a few seconds contact 104 emerges from the mercury layer and a continued conductive relationship is maintained in the mercury layer by contacts 100 and 102. As in the second modification of this invention described above, the electrical contacts when in a non-conductive position are exposed to the inert gas as shown by contact 100 in FIG- URE 7 and by contact 104 in FIGURE 8. In the olf position of FIGURE 7, only contact 104 is in the mercury layer and thus no circuit is closed. The mercury layer is seen to be approximately level with the horizontal member of wall portion 70 and it is seen that the tip of the straight wall portion 78 is slightly below the mercury surface. This assures that the oil 38 will not contact the electrical contact 100 and 102. In the initial on position, the mercury passes down passages 92, 96, and through circular depression 74 to force the oil through passages 82, 84 and 86 into the upper portion of the housing. Again, the flow of mercury is delayed by passage of oil through the bore 62 which has its opening adjusted by needle valve 50. In the final on position as shown in FIGURE 8, the tip of straight wall member is slightly below the mercury surface, oil is seen to have moved into passage 96, and another of the extending legs of the three pronged member 70 is now horizontal and substantially even with the mercury surface.

This modification of the invention also prevents the presence of the oil in the arcing chamber as mentioned above. Were the oil to be present in the chamber while the electrical contacts close the circuit, the sparking would cause the oil to be carbonized. Besides coating the electrical contacts, the carbonized material would fluff off and contaminate the oil layer eventually to cause the oil to become sluggish.

The mercury switch of this invention may also be modified to include a check valve or clash pot positioned within the passage 26 or passage 62. The check valve is designed to be fully open in one position to permit rapid flow of oil through an enlarged passage 26 or 62. In a normally closed position the check valve does not close completely, but contains a small opening which permits the flow of oil through the check valve to be closely controlled by the needle valve. Thus, when the mercury switch is turned on, the enlarged opening provided by the check valve assists the flow of mercury. When the switch is turned off, the reduced opening permits additional control of the oil flow.

Since many differentembodiments of this invention may be made without departing from the spirit and scope of this invention, it is to be understood that the specific embodiments described in detail herein are not to be taken in a limiting sense since the scope of the invention is best defined by the appended claims.

We claim:

1. A time-delay switch comprising a rotatable housing of non-conductive material,

baflle means in said housing separating the interior of said housing, into communicating compartments at one end of said baifle, said bafile means having adjustable fluid passage means therein,

a pair of electrical contacts entering said interior of said housing,

said housing containing mercury and a non-conductive liquid immiscible with said mercury, whereby in a first rotative position of said housing said electrical contacts are substantially immediately immersed in said mercury to form a conductive circuit across said contacts, and in a second rotative position of said housing said contacts are immersed in said nonconductive liquid so that said circuit is broken, and said adjustable fluid passage means meters the flow of said non-conductive fluid through said passage such that said metered flow controls the flow of said mercury around said bafile means to provide a timedelay effect between said first to second positions.

2. A time-delay switch comprising;

a cylindrical housing of non-conductive material, said housing being rotatable about its axis,

baflle means in said housing separating the interior of 7 1 said housing into communicating compartments at one end of said bafile, said baifle means having adjustable fluid passage means therein,

a pair of electrical contacts entering said interior of said housing,

said housing containing mercury and a non-conductive liquid immiscible with said mercury whereby in a first rotative position of said housing said electrical contacts are substantially immediately immersed in said mercury to form a conductive circuit across said contacts, and in a second rotative position of said housing said contacts are immersed in said non-conductive liquid so that said circuit is broken, and said adjustable fluid passage means meters the flow of said non-conductive fluid through said passage such that said metered flow controls the flow of said mercury around said bafiie means to provide a timedelay effect between said first to second positions.

3. A time delay switch as described in claim 2 in which said baffie means includes a thin wall extending diametrically substantially across the interior of said housing so as to divide said interior into two compartments and to provide a baflied passage betwen the end of said wall and said interior housing for the flow of said mercury.

4. A time delay switch as described in claim 3 in which said adjustable fluid passage means in said baffle includes an adjustable slide valve in the end of said baffle adjoining the said housing, said slide valve adjustable exteriorly of said housing.

5. A time delay switch as described in claim 4 in which said electrical contacts comprise a pair of contacts entering the flat sides of said housing longitudinally opposite each other and within the same compartment of said housing.

'6. A time delay switch as described in claim 5 in which said electrical contacts include a second pair of contacts entering the flat sides of said housing longitudinally opposite each other and within a second of the two said compartments, said first and said second pairs of electrical contacts positioned so that both of said pairs are within said non-conductive layer when said switch is in an off position and so that initially in an on position said both pairs of electrical contacts are in conductive relationship with said mercury.

7. A'time delay switch comprising a cylindrical housing of non-conductive material, said housing being rotatable about its axis,

baffle means in said housing, said baffle means comprising a thin wall extending diametrically substantially across the interior of said housing separating said housing into two communicating compartments, said wall providing a baffled passage between the end of said wall and said interior housing.

adjustable fluid passage means in said baffle com-prising an adjustable slide valve in the end of said baffle adjoining said housing, said slide valve means adjustable exteriorly of said housing,

a first pair of electrical contacts entering the flat sides of said housing longitudinally opposite each other and within the first of said compartments.

a second pair of electrical contacts entering the flat sides of said housing longitudinally opposite each other and within the second of said compartments,

said housing containing mercury and a non-conductive liquid immiscible with said mercury,

said first pair and said second pair of electrical contacts positioned so that both of said pairs are within said non-conductive layer when said switch is in an off position and so that initially in an on position said both pairs of electrical contacts are in conductive relationship with said mercury, and

said adjustable slide valve meters the flow of said nonconductive liquid through said valve so that said metered flow controls the flow of said mercury around said bafile means to provide a time delay effect betwen said initial on position and a final on position.

8. A time delay switch comprising a cylindrical housing of non-conductive material, said housing being rotatable about its axis,

baffle means in said housing separating the interior of said housing into communicating compartments, said baflie means having adjustable fluid passage means therein,

a pair of electrical contacts entering said interior of said housing,

said housing containing mercury, a non-conductive liquid immiscible with said mercury, and an inert whereby in a first rotative position of said housing said electrical contacts are immersed in said mercury to form a conductive circuit betwen said contacts, and

whereby in a second rotative position of said housing said contacts are exposed to said inert gas to break said conductive circuit, and

said adjustable fluid passage mean-s meters the flow of said non-conductive liquid through said passage such that said metered flow controls the flow of said mercury around said baffle means to provide a time delay effect between the conductive on and non-conductive off positions of said switch.

9. A time delay switch comprising a cylindrical housing of non-conductive material, said housing being rotatable about its axis,

bafiie means in said housing separating the interior of said housing into communicating compartments, said baflie means comprising a first wall portion having parallel sides extending perpendicularly inwardly from the interior wall of said housing to a position less than halfway across said housing,

a second wall portion having an approximately arcuate member substantially defining an interior area of said housing to provide a passage between said arcuate member and the interior wall of said housing, said arcuate member radially removed from said first wall portion, said second wall portion having a transversely inwardly extending straight wall member adjacent that end of said arcuate member farthest removed from said first wall portion, said straight wall member providing a passage between said straight wall member and a thickened interior wall of said housing,

a third wall portion positioned between said first wall portion and said second wall portion, said third wall portion having a straight wall member parallel to said straight wall member of said second wall portion to provide a passage between said straight wall member of said second and third wall portion and a passage between the end of said third wall portion and said second wall port-ion, and said third wall portion having an arcuately extending member integrally extending from said straight wall member of said third wall, said arcuate member providing a passage between said arcuate member of said third wall and the end of said first wall, the end of said arcuate member of said third wall approaching said thickened interior wall to provide a passage therebetween,

adjustable fluid passage means in said first wall portion comprising a slide valve positioned in said first wall to vary said passage between said first wall portion and said arcuate member. of said third wall,

a pair of electrical contacts entering the flat sides of said housing longitudinally opposite each other and within the passage between said straight wall member of said second wall portion and said thickened interior of said housing,

said housing containing mercury, a non-conductive liquid immiscible with said mercury and an inert gas,

whereby in a first rotative position of said housing said electrical contacts are immersed in said mercury to form a conductive circuit between said contacts, and

whereby in a second rotative position of said housing said contacts are exposed to said inert gas to break the conductive circuit, and

said adjustable fluid passage means meters the flow of said non-conductive liquid through said passage such that said metered flow controls the flow of said mercury around said bafile means to provide a time delay effect between the conductive on and non-conductive ofi positions of said switch.

10. A time delay switch comprising a cylindrical housing of non-conductive material, said housing being rotatable about its axis,

bafiie means in said housing separating the interior of said housing into communicating compartments, said baffle means comprising a first wall portion having parallel sides extending perpendicularly inwardly from the interior wall of said housing to a position approximately centrallyof said housing,

a second wall portion having three equally spaced straight members extending from a position near the center of said housing, said second wall portion providing a passage between said second wall portion and the end of said first wall portion approximately centrally of said housing,

a third wall portion having an arcuate member forming a passage between said arcuate member of said third wall portion and the interior wall of said housing, a first end of said arcuate member forming a passage between said arcuate member and said first wall portion, said third wall portion having a transversely inwardly ex tending straight member adjacent a second end of said arcuate member to provide a passage between said straight member and said second wall portion and to provide a passage between said straight member and said interior wall of said housing,

a fourth wall portion positioned at opposite side of said housing from said third wall portion so that said first wall portion and said second wall portion are between said third and said fourth wall portions, said fourth wall portion having an arcuate member forming a passage between said arcuate member of said fourth wall portion and said interior wall of said housing, a

first end of said fourth wall arcuate member forming a passage between said fourth wall arcuate member and said first wall portion, said fourth wall portion having a transversely inwardly extending straight member adjacent a second end of said fourth wall arcuate member to provide a passage between said fourth wall straight member and said second wall portion and to provide a passage between said fourth wall straight member and said interior wall of said housing,

adjustable fluid passage means in said first wall portion comprising a slide valve positioned in said first Wall to vary said passage between said second Wall portion and said end of said first wall,

a pair of electrical contacts entering the fiat sides of said housing longitudinally opposite each other and within the passage between said third Wall straight member and said interior of said housing,

a single electrical contact entering the flat side of said housing within the passage between the said fourth wall straight member and the interior of said housing,

said housing containing mercury, a non-conductive liquid immiscible with said mercury, and an inert gas,

whereby initially in a first rotative position of said housing said pair of electrical contacts and said single electrical contact are immersed in said mercury to form a conductive circuit, and finally in said first rotative position only said pair of electrical contacts are immersed in said mercury to form a conductive circuit, and

whereby in a second rotative position of said housing said pair of electrical contacts are exposed to the said inert gas to break said conductive circuit, and

said adjustable fluid passage means meters the flow of said non-conductive liquid through said passage such that said metered flow controls the fiow of said mercury around said bafiie means to provide a time delay eifect between said initial first rotative position and said final first rotative position.

8/1940 Cook 20033 10/1966 Worth 20033 BERNARD A. GILHEANY, Primary Examiner.

E, SPRINGBORN, Assistant Examiner. 

1. A TIME-DELAY SWITCH COMPRISING A ROTATABLE HOUSING OF NON-CONDUCTIVE MATERIAL, BAFFLE MEANS IN SAID HOUSING SEPARATING THE INTERIOR OF SAID HOUSING, INTO COMMUNICATING COMPARTMENTS AT ONE END OF SAID BAFFLE, SAID BAFFLE MEANS HAVING ADJUSTABLE FLUID PASSAGE MEANS THEREIN, A PAIR OF ELECTRICAL CONTACTS ENTERING SAID INTERIOR OF SAID HOUSING, SAID HOUSING CONTAINING MERCURY AND A NON-CONDUCTIVE LIQUID IMMISCIBLE WITH SAID MERCURY, WHEREBY IN A FIRST ROTATIVE POSITION OF SAID HOUSING SAID ELECTRICAL CONTACTS ARE SUBSTANTIALLY IMMEDIATELY IMMERSED IN SAID MERCURY TO FORM A CONDUCTIVE CIRCUIT ACROSS SAID CONTACTS, AND IN A SECOND ROTATIVE POSITION OF SAID HOUSING SAID CONTACTS ARE IMMERSED IN SAID NONCONDUCTIVE LIQUID SO THAT SAID CIRCUIT IS BROKEN, AND SAID ADJUSTABLE FLUID PASSAGE MEANS METERS THE FLOW OF SAID NON-CONDUCTIVE FLUID THROUGH SAID PASSAGE SUCH THAT SAID METERED FLOW CONTROLS THE FLOW OF SAID MERCURY AROUND SAID BAFFLE MEANS TO PROVIDE A TIMEDELAY EFFECT BETWEEN SAID FIRST TO SECOND POSITIONS. 